Automatic safety ignition switch



April12,1949. F. w. MURPHY Em 2,467,333

AUTOMATIC SAFETY IGNITION SWITCH Filed Aug. 18, 1947 www5 Patented Apr. l2, 1949 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to switches for automatically breaking the ignition circuit of an internal combustion engine or the like when the oil pressure drops to a predetermined low point, when the engine temperature rises to a determined high point, or when it is desired to manually shut down the engine by breaking the ignition circuit.

This switch is designed primarily for use on large internal combustion engines which are operated for long periods of time such as at power plants, pumping stations and the like where a single operator may supervise a number of engines or where the engines are run with little or no attention for prolonged periods of time. Such engines are apt to develop troubles which are not readily noted by the attendant and which would be exaggerated by the continued operation of the engine. As most all engine iailuresare noted either by a drop of oil pressure or by a rise of the temperature, suitable switches responsive to these engine failure symtoms are connected into the engine ignition circuit for breaking the ignition circuit upon the arising of excessive determined conditions of either' the oil pressure or engine temperature. As it is not desirable that these symptom responsive switches be connected directly in the ignition circuit, it is an object of this invention to provide a' switch in the ignition circuit upon which the pressure and temperature switches act as relays for breaking the ignition circuit.

Another object of this invention is to provide a safety cut-off switch of the kind to be more particularly described hereinafter, having a switch with an electro-magnetic operator for opening the switch, a manual reset button for closing the switch when once opened, the reset button also opening the circuit to the electro-magnetic switch operator when the button is being pushed to reset position so that the operator will not be biasing the switch open at the same time the button is trying to close the switch.

Still another object of this invention is to provide a switch of this kind having a manually operable switch connected substantially in parallel to the relays for manually closing the switch operator circuit when it is desired to stop the engine with the temperature and pressure relay switches in the open or normal position.

With the above and other objects in view, our invention consists in the arrangement, combination and details of construction disclosed in the dra-wings and specification, and then more particularly pointed out in the appended claims.

In the drawings,

Figure 1 is a longitudinal section through an ignition safety cut-off switch constructed accoi-ding to an embodiment of our invention,

Figure 2 is a transverse section taken on the line 2-2 of Figure 1,

Figure 3 is a fragmentary transverse section, partly broken away, taken on the line 3-3 of Figure l; and

Figure 4 is a diagrammatic wiring diagram of the circuits through the switch.

Referring to the drawings, the numeral I designates generally a switch connected in the C ignition circuit of an internal combustion engine which is connected to a pressure responsive switch II and a temperature responsive switch I2 for breaking the ignition circuit when the oil pressure switch I I or engine temperature switch I2 is closed.

The safety switch I0 is formed of a housing I4 which is open, as at the bottom. A base plate I 5 is provided for closing the bottom of the housing I4 and enclosing the switch operating parts therein. The housingl I4 is fixed to the base plate I5 by downwardly extending lugs or ears I6 on each end of the housing I4 which are adapted to be crimped over the end edges of the plate l5 or secured by other suitable attaching means.

Three terminals, B, C, and G are carried on the lower side of the plate I5, which provide the terminals for the switch IU, for nnecting the switch ID in the ignition coil circuit and to the pressure and temperature switches II and I2. The terminals B, C, and G are insulated from each other and from the base plate I5 by a strip il of insulating material fixed between the base and the terminals.v An L-shaped attaching or mounting bracket I3 is fixed to or formed on one edge of the base plate I5 for mounting the switch I0 on a suitable panel and the cover or housing I4 may be removed while the base I5 is secured to the panel.

A second strip of insulating material I9 is xed on the upper side of the base plate I5 for insulating the inner parts of the switch I0 there.

from.

An electro-magnet 2li is xed on the base I5 substantially in the center thereof, The electromagnet 20 includes a coil 2| about a core 22 in the conventional form of such magnets. An armature 24 is associated with the magnet 20 and is adapted to be drawn toward the end of thereof.

at one end to the upper end of the arm 2l ofv the bracket 25, and the armature 24 is fixed on the other end oi the spring 28 so the armature is resiliently carried by the bracket above the core 22 of the coil 2l, the armature being biased upwardly by the spring 28. A stop member 29 is carried by the upper end of the electromagnet 2@ and is formed with a horizontal upper arm 3d. The upper side of the armature 2d is adapted to engage the lower side of the arm 3B for limiting the upward movement of the armature caused by the spring 2B.

A hook or latch 3l is carried by the free end of the armature 24 and is bevelled or formed with a downwardly and outwardly inclined terminal end over whicha latch is adapted to slide.

A latch 32 is carried by the base I5 above the insulating strip I9 adjacent the electro-magnet 20 opposite from the bracket 25 and adjacent the free end of the armature 24. The keeper 32 is formed of an L-shaped length of at resilient metal. The lower arm 34 is xed to lthe plate I5 and the vertical arm 35a is formed with cuit not lead at c, so that the electro-,magnet i circuit willbe completed or closed by the switches Il and/or I2 being closeddue to an abnormal engine condition. When the electro-magnet is energized the armature 24 is drawn down to release the latch 32 so that both the engine ignition circuit and the electro-magnet circuit will be open or broken to stop the engine and cut the battery out of both circuits.

For grounding the electro-magnet circuit manually to stop the engine, a switch 35 is provided Which is carried by the switch IB. As the housing I4 is grounded through the base I5 and bracket I8, a contact member carried by the terminal G, when engaged with .the housing It will ground the electro-magnet circuit parallel to the switches Il and l2 for breaking the ignition circuit. A fxed contact 3G is carried by the housing lil, and a resilient arm 3l carried by the Gr terminal carries a correlated Contact 38. A'n insulated knob 39 is fixed on the upper end of the arm 3l so an engineer may manually close the switch 35 by pressing the contact 38 into engagement with the contact 35.

A spring-pressed reset button l0 is carried by the housing lil adjacent the latch 32. The reset button 40 is made of insulating material and is slidable through the end wall of the housing I4.'

The reset button 4I) is insulated from the housing I4 and the adapter fittings or bearings 4I for slidably supporting the button 30 are also insulated as by the grommet t2. A spring 4i! is 'carried by the fittings 4I for biasing the reset a rectangular opening 33 adjacent the upper end The extreme upper end of the latch 32 is inclined upwardly and inwardly toward the hook 3i' on the armature 24. The latch 32 is biased outwardly away from the armature 24 and the hook 3l is adapted for engagement into the opening 33 so the hook will engage the extreme upper end of the latch 32 for connecting the keeper and armature in hooked relation. The spring 28 biases the armature to hooked or keeper engaged relation and the electro-magnet, when energized, draws the armature downward, so the biased latch is spring-pressed away from the armature in a direct breaking position.

The ignition circuitl of an engine is to be connected through the latch 32 and armature 24. The keeper 32 is connected by suitable circuit connecting means to the terminal B of the switch Ill which, in turn, is adapted to be connected to the hot lead of the battery for the engine. The bracket 25 is connected by suitable circuit connecting means to the terminal C of the switch l0, which terminal C, in turn, is adapted to be connected to the ignition coil of the engine. The ignition circuit then is completed through the terminal B, latch 32, armature 24, bracket 25 and terminal C. When the latch is out of engagement with the armature 24, the ignition cir cuit is opened and the engine will stop.

For stopping the engine automatically when abnormal running conditions arise, a normally open pressure responsive switch I2 and temperature responsive switch II are provided for connection to the electro-magnet 20. The switches or relays II and I2 are adapted to be closed when the engine temperature or oil pressure rise or drop respectively to a predetermined value. One side of each of the switches II and I2 is adapted to be connected to the battery ground and the other side to the terminalG of the switch Ill. One end of the coil 2l is connected to the G terminal and the other end to the ignition cirbutton outwardly to an idle or free position.

g5 The inner end of the reset button 4I) is en- @the fittings dI, spring 44 and wall of the housing I4.

It is obviously desirable and sometimes necessary to open the circuit of the electro-magnet 20 while the ignition circuit is being reset. Y Rather than provide a separate switch and separate switch operator for this purpose, the switch I0 is designed so that pressing the button 4B in to.

reset the electromagnet circuit is opened simultaneously and remains open until the button 40 is released to its normal extended position. A switch i5 is associated with and operated by the reset button ill). A pair of metal contact strips 36 are carried by the base i5 on opposite sides of the but t0n il Within the housing I6. The strips or contacts c3 are fixed on an upturned end of the arm 3d and insulated therefrom by an insulating block d'1. One contract 46 is connected to the ground terminal G, and the other contact i6 is connected to the free or ground end of the coil 2l of the electro-magnet 20. A bridging member 48 is xed on the extreme inner end of the button or rod d@ and is biased by the spring 4d into normal contact with-the contact members 46 for normally closing the ground connection of the coil 23. When the button 40 is pressed inwardly to reset the keeper into engagement with the armature 24, the bridging connector 48 'is moved away from the contact strips to open the circuit to the electromagnet irrespective of the positions of the switches II, I2 and 35. The contacts 46 are insulated from the bearing 4I by an insulating washer 49 and the inner anged end of the bearings 4l is insulated by an insulating sheet 5l).V

We do not mean to confine ourselves to the exact details of construction herein disclosed, but claim .all variations falling within the purview ci the appended claims.

What we claim is:

1. An automatic safety ignition switch comprising a base plate, a battery terminal post on said base insulated therefrom, an insulated coil terminal post on said base, a ground terminal post on said base insulated therefrom, an electromagnet dried on said base including a core and' windings thereabout, a spring-pressed armature above said core biased out of engagement with said core, a cover tor said switch xed on said base, a resilent latch carried by said base and adapted when in set position to engage said armature to close the ignition circuit, an outwardly spring-pressed reset button slidably supported on said cover and extending therethrough engageable with said latch member, a pair of contact members carried by said base within said cover on opposite sides of said reset button, a bridging member carried by said button for connecting said contact members in the normal springpressed position of said reset button, circuit connecting means between one of said contact members and said ground post, the other contact member and one end of said winding, the other end of said winding and said coil terminal post, said coil terminal post and said armature, and between said latch member and said battery contact post whereby said latch will become disengaged irom said armature upon initial grounding of said ground contact post.

2. An automatic safety ignition switch as set forth in claim 1, including a manually operable resilient contact member carried by said ground terminal post engageable with said cover for grounding the switch.

FRANK W. MURPHY. LEWIS CARLTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

